System, module, and method for generating HUD image data from synthetic vision system image data

ABSTRACT

A present novel and non-trivial system, apparatus, and method for generating HUD image data from synthetic image data is disclosed. Based on a multi-channel pixel intensity data set generated by a synthetic vision system, a single-channel pixel intensity data set representative of a lighted solid image of terrain comprised of a plurality of intensities of one color may be generated. The single-channel pixel intensity image data set may be determined as a function of multi-channel pixel intensity data set and channel weighting, where channel weighting may be based on sky and/or terrain colors employed by an SVS. Based on the multi-channel pixel intensity data set, a three-dimensional perspective scene outside the aircraft may be presented to the pilot on a HUD combiner. Also, the multi-channel pixel intensity data set may be modified by using at least one chroma key, where such chroma key may be assigned to a specific multi-channel pixel intensity value.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention pertains to the field of cockpit indicators or head-updisplay (“HUD”) units that provide terrain information to the pilot orflight crew of an aircraft using image data generated by a syntheticvision system (“SVS”).

2. Description of the Related Art

Modern avionics systems employ HUD and Head-Down Display (“HDD”)indicating systems for providing tactical flight information to thepilot. In a HUD system, a HUD unit is mounted in front of the pilot atwindshield level and is directly in the pilot's field of vision. The HUDsystem is advantageous because the display is transparent allowing thepilot to keep his or her eyes “outside the cockpit” while the displayunit provides tactical flight information to the pilot. In a HDD system,a tactical flight display is mounted in the cockpit instrument paneldirectly in front of the pilot and below windshield level. To view thepresentation of information on a display unit of a HDD system, a pilotmust look down into the cockpit, causing him or her to take his or hereyes from the outside scene of the aircraft.

Modern avionics systems may employ an SVS for displaying terraininformation to both HDD and HUD systems. The SVS system is advantageousin an HDD and HUD indicating system because it presents terraininformation of the scene outside the aircraft (“synthetic scene”),thereby enhancing the situational awareness of the pilot. In an HDDsystem, a lighted solid image of terrain and objects (e.g., obstaclesand runways) may be represented on an HDD unit as a realistic,intuitive, three-dimensional perspective using terrain color codingaccording to elevation that mimics coloring used in aviation-relatedcharts and publications.

U.S. Pat. No. 8,264,498 entitled “System, Apparatus, and Method forPresenting a Monochrome Image of Terrain on a Head-Up Display Unit,”which is hereby incorporated by reference in its entirety disclosed anovel and non-trivial system, apparatus, and method for presenting amonochrome, three-dimensional lighted solid image of terrain to thepilot on a HUD unit based upon an image data set comprised of terraindata and color intensity data. Color intensity data could be included ina multi-channel pixel intensity data set.

BRIEF SUMMARY OF THE INVENTION

The embodiments disclosed herein present novel and non-trivial system,apparatus, and method for generating HUD image data from synthetic imagedata generated by an SVS. The synthetic image data could comprise amulti-channel pixel intensity data set representative of a lighted solidsynthetic image which could be converted to a single-channel pixelintensity data set, where such single-channel pixel intensity data setis provided to a HUD system for display of a monochrome,three-dimensional lighted solid image of the synthetic scene on a HUDcombiner unit.

In one embodiment, a system is disclosed for generating HUD image datafrom synthetic image data. The system comprises an SVS for providingsynthetic image data, an image generating (“IG”) processor, and a HUDsystem. The IG processor could receive a multi-channel pixel intensitydata set and generate a single-channel pixel intensity data setrepresentative of a lighted solid terrain image comprised of a pluralityof intensities of one color; the single-channel pixel intensity data setmay be generated as a function of the multi-channel pixel intensity dataset and channel weighting, where channel weighting may be based on skyand/or terrain colors employed by the SVS. In another embodiment, themulti-channel pixel intensity data set may be modified by using at leastone chroma key, where such chroma key may be assigned to a specificmulti-channel pixel intensity value. After the image data set has beengenerated, the IG processor could provide the single-channel pixelintensity data set to a HUD system for displaying an image representedin the data set on a HUD combiner unit.

In another embodiment, a module is disclosed for generating HUD imagedata from synthetic image data. The module comprises an inputcommunications interface, an IG processor, and an output communicationsinterface. The input communications interface facilitates the receipt ofdata from at data sources. The IG processor could receive amulti-channel pixel intensity data set and generate a single-channelpixel intensity data set representative of a lighted solid terrain imagecomprised of a plurality of intensities of one color; the single-channelpixel intensity data set may be generated as a function of themulti-channel pixel intensity data set and channel weighting, wherechannel weighting may be based on sky and/or terrain colors employed bythe SVS. In another embodiment, the multi-channel pixel intensity dataset may be modified by using at least one chroma key, where such chromakey may be assigned to a specific multi-channel pixel intensity value.After the image data set has been generated, the IG processor couldprovide the single-channel pixel intensity data set to a HUD system fordisplaying an image represented in the data set on a HUD combiner unit.

In another embodiment, a method is disclosed for generating HUD imagedata from synthetic image data. Multi-channel pixel intensity data setcould be received and an image data set could be generated as a functionof the multi-channel pixel intensity data set and channel weighting,where channel weighting may be based on sky and/or terrain colorsemployed by the SVS. In another embodiment, the multi-channel pixelintensity data set may be modified by using at least one chroma key,where such chroma key may be assigned to a specific multi-channel pixelintensity value. Single-channel pixel intensity data set may be providedto a HUD system for displaying an image represented in the data set on aHUD combiner unit.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts a block diagram of a HUD image data generating system.

FIG. 2A depicts an example of a typical wide field of view HUD such asfound in commercial airliners.

FIG. 2B depicts an example of a typical glareshield mounted HUD such asfound in a fighter aircraft.

FIG. 3A provides an exemplary illustration of an HDD unit with flightsymbology depicted against the background a synthetic scene generatedfrom an RGB color model.

FIG. 3B provides an exemplary illustration of an HDD unit without flightsymbology depicted against the background a synthetic scene generatedfrom an RGB color model.

FIG. 3C depicts the synthetic scene of FIG. 3B where the right-half ofthe image has been converted to a single-channel image using a BT.601formula.

FIG. 3D depicts the synthetic scene of FIG. 3B where the right-half ofthe image has been converted to a single-channel image using a BT.709formula.

FIG. 3E depicts the synthetic scene of FIG. 3B where the right-half ofthe image has been converted to a single-channel image using a red-onlysingle-channel color model.

FIG. 3F depicts the synthetic scene of FIG. 3B where the right-half ofthe image has been converted to a single-channel image using agreen-only single-channel color model.

FIG. 3G depicts the synthetic scene of FIG. 3B where the right-half ofthe image has been converted to a single-channel image using a blue-onlysingle-channel color model.

FIG. 4 provides a flowchart illustrating a method for generating HUDimage data from synthetic image data.

DETAILED DESCRIPTION OF THE INVENTION

In the following description, several specific details are presented toprovide a thorough understanding of embodiments of the invention. Oneskilled in the relevant art will recognize, however, that the inventioncan be practiced without one or more of the specific details, or incombination with other components, etc. In other instances, well-knownimplementations or operations are not shown or described in detail toavoid obscuring aspects of various embodiments of the invention.

FIG. 1 depicts a block diagram of a HUD image data generating system 100suitable for implementation of the techniques described herein. The HUDimage data generating system 100 of an embodiment of FIG. 1 includessynthetic vision system (“SVS”) 110, navigation system 120, an imagegenerating (“IG”) processor 130, and a head-up display (“HUD”) system140.

An SVS 110 may generate or produce an image data set (interchangeably,“synthetic scene data” or “synthetic image data”) representative of athree-dimensional perspective scene outside of an aircraft(interchangeably, “synthetic scene” or “synthetic image”), where suchimage could be provided to a display system or display unit of thedisplay system, and the display unit presents an image of the syntheticscene to the pilot. As embodied herein, aircraft could mean any vehiclewhich is able to fly through the air or atmosphere including, but notlimited to, lighter than air vehicles and heavier than air vehicles,wherein the latter may include fixed-wing and rotary-wing vehicles.

In one embodiment, the synthetic scene may include terrain and/orobstacles. In an additional embodiment, the synthetic scene data couldinclude data representative of shading effect and/or texturing effects.As embodied herein, the image data set generated or produced by an SVS110 could comprise a multi-channel pixel intensity data set, and suchmulti-channel pixel intensity data could comprise color intensity data.Shading effects and/or texturing effects contained in color intensitydata were disclosed in U.S. Pat. No. 8,264,498 entitled “System,Apparatus, and Method for Presenting a Monochrome Image of Terrain on aHead-Up Display Unit” which is hereby incorporated by reference in itsentirety.

Location highlighters may address the difficulty of identifying distantobjects as disclosed by Yum et al in U.S. Pat. No. 8,094,188 entitled“System, Apparatus, and Method for Enhancing the Image Presented on anAircraft Display Unit through Location Highlighters” which is herebyincorporated by reference in its entirety. The use of a locationhighlighter such as a three-dimensional shape can improve a pilot'sability to determine the location of an airport or other objectpresented on a display unit by enhancing the image presented on anaircraft display unit without interfering with the presentation offlight symbology. Although the disclosed use of location highlightersincluded the ability to include information within the highlighter,there could be times when displaying such information would interferewith the simultaneous display of flight symbology and athree-dimensional perspective view of terrain.

A synthetic scene may be presented with topographical coloring on ahead-down display (“HDD”) unit to provide a pilot with a clear andintuitive understanding of the scene outside the aircraft. An HDD ismounted in the cockpit instrument panel directly in front of the pilotand below windshield level. To view the presentation of information on aHDD display unit, a pilot must look down into the cockpit, causing himor her to take his or her eyes from the outside scene of the aircraft.

Different terrain elevations of a synthetic scene may be presented withdifferent colors on an HDD unit, where such colors could correspond to acoloring scheme used on aeronautical charts. For example, the color ofthe low elevation terrain may be comprised of shades of green, hilly ormountainous terrain may be comprised of shades of brown, and the sky maybe comprised of a shade of blue.

A navigation system data 120 may include, but is not limited to, anair/data system, an attitude heading reference system, an inertialguidance system (or inertial reference system), a global navigationsatellite system (“GNSS”) (or satellite navigation system), and a flightmanagement computing system, all of which are known to those skilled inthe art. As embodied herein, a navigation system 110 could providenavigation data including, but not limited to, aircraft positioncomprising of geographic position and altitude to an IG processor 130for subsequent processing as discussed herein.

An IG processor 130 could have provided the image data received by a HUDsystem 140. An IG processor 130 may be any electronic data processingunit which executes software or source code stored, permanently ortemporarily, in a digital memory storage device or computer-readablemedia (not depicted herein) including, but not limited to, RAM, ROM, CD,DVD, hard disk drive, diskette, solid-state memory, PCMCIA or PC Card,secure digital cards, and compact flash cards. An IG processor 130 maybe driven by the execution of software or computer instruction codecontaining algorithms developed for the specific functions embodiedherein; alternatively, an IG processor 130 may be implemented as anapplication-specific integrated circuit (ASIC). Common examples ofelectronic data processing units are microIG processors, Digital SignalIG processors (DSPs), Programmable Logic Devices (PLDs), ProgrammableGate Arrays (PGAs), and signal generators; however, for the embodimentsherein, the term IG processor is not limited to such processing unitsand its meaning is not intended to be construed narrowly. For instance,an IG processor could also consist of more than one electronic dataprocessing unit. As embodied herein, an IG processor 130 could be anyprocessor(s) used by or in conjunction with any other system of theaircraft including, but not limited to, a processor of a syntheticvision system 110, a HUD system 140, or any combination thereof.

An IG processor 130 may receive input data from various systemsincluding, but not limited to, a synthetic vision system 110 and anavigation system 120. An IG processor 130 may be electronically coupledto a synthetic vision system 110 and a navigation system 120 tofacilitate the receipt of input data; as embodied herein, operativelycoupled may be considered as interchangeable with electronicallycoupled. An IG processor 130 may provide output data to various systemsincluding, but not limited to, an HUD system 140. An IG processor 130may be electronically coupled to a HUD system 140 to facilitate theproviding of output data. It is not necessary that a direct connectionbe made; instead, such receipt of input data and the providing of outputdata could be provided through a data bus or through a wireless network.It should be noted that data, as embodied herein for any source orsystem including a navigation system, could be comprised of any analogor digital signal, either discrete or continuous, which could containinformation.

As embodied in FIG. 1, a HUD system 140 may be comprised of a pluralityof components including, but not limited to, a HUD image projection unit142 and a partially transparent and reflective optic commonly referredto as a combiner unit 144. In general, a HUD uses a combination oflenses to create a collimated image. Lens designs that achieve thenecessary optical performance tend to be complex and expensive,especially when the FOV is high and the diameter of the lens is large.

For the purpose of illustration and not for the purpose of limitation,FIGS. 2A and 2B provide a mere two examples of HUD configurations fromthe many configurations known to those skilled in the art. For example,FIG. 2A shows an optical layout of a HUD with a wide field of view,which consists of an image projection unit that employs a relay lensassembly mounted over the viewer's head and a combiner unit locatedforward of the viewer that may be mounted in an aircraft such as acommercial aircraft. As shown, the relay lens assembly is used to forman intermediate image one focal length away from a transparent combiner,which, in turn, functions as a collimating mirror forming collimatedbeams of light. In another example, FIG. 2B shows a HUD assemblycomprised of a HUD image projection unit and combiner unit that may bemounted in the glareshield of an aircraft such as a military fighteraircraft. As shown, beams of light leave a group of field flatteninglenses, strike a reflecting mirror or prism, and pass through convex andconcave lenses to form collimated beams of light. As shown in theexamples of FIGS. 2A and 2B, a typical HUD image projection unit 142comprises of a complex array of lenses, prisms, and/or mirrors. Asembodied herein, a HUD system 140 could comprise any HUD imageprojection unit 142 which receives optical image input and projects theimage onto a combiner unit 144 comprising of one or more combiners.

A combiner unit 144 may be used as a display device used in a HUD system140. A combiner unit 144 may comprise of one surface as shown in FIG. 2Aor a plurality of surfaces as shown in FIG. 2B. A combiner unit couldcomprise a transparent, world scene while simultaneously viewinginformation contained in an image reflected toward the viewer by one ormore combiners. As a display device, a combiner unit 144 may presenttactical flight information and/or a synthetic scene. As embodiedherein, tactical flight information displayed on a combiner unit 144could be information relevant to the instant or immediate control of theaircraft, whether the aircraft is in flight or on the ground. Asembodied herein, a combiner unit 144 may depict the synthetic scene as alighted solid image as disclosed in the U.S. Pat. No. 8,264,498 asdiscussed above.

The advantages and benefits of the embodiments discussed herein may beillustrated by showing examples depicting synthetic images that couldhave been generated or produced by an SVS 110 using a multi-channelcolor model, where the synthetic image is then depicted after beingconverted to a single-channel using more than one weighted conversionformulas. FIG. 3A provides an exemplary illustration of an HDD unit withflight symbology depicted against the background a synthetic scene whichhas a runway in the center of it; the scene in FIG. 3A could beindicative of an aircraft that is flying a final approach to a runwayfor landing. It should be noted that the symbology depicted on the HDDunit shown in FIG. 3A has been made minimal intentionally for the sakeof presentation and is not indicative of the plurality of indications orinformation with which it may be configured. Because the indications orinformation shown in FIG. 3A are well-known to those skilled in the art,a discussion of the specific tactical information shown in FIG. 3A isnot provided herein.

FIG. 3B provides an exemplary illustration of an HDD unit with thesynthetic scene of FIG. 3A without the depiction of flight symbology.The same synthetic scene will be used for FIGS. 3C through 3G,inclusive, but a conversion has been made to the right-half of each toillustrate the differences of the synthetic scene converted from amulti-channel color model employing a plurality of channels to asingle-channel color model. For the purposes of discussing FIGS. 3Cthrough 3G, inclusive, the colors synthetic image produced by an SVSwill be based on the RGB color model having an 8-bit color scale foreach channel ranging from 0 to 255. Although the following discussionwill be drawn to this specific color model, the embodiments herein arenot limited to such color model only but include any color modelemploying any color scale.

FIG. 3B depicts a runway having a black runway border 202, a magentalocation highlighter 204 highlighting the location of the runway, and asky 206 having the color of “sky blue.” For the colors of these threeitems, the following intensities of the RGB color model of the syntheticscene are the following: black (0, 0, 0), magenta (255, 0, 255) and skyblue (0, 136, 204).

A single-channel color model may be derived by applying weights to eachchannel of the multi-channel color model to arrive at a weighted sum,where the sum of the weights is one. For example, the RadiocommunicationSector of the International Telecommunications Union (“ITU-R”) haspublished standards for converting a three-channel RGB model to asingle-channel grayscale color model. ITU-R Recommendation BT.601(“BT.601”) provides formatting standards for digital television, andITU-R Recommendation BT.709 (“BT.709”) provides formatting standards forhigh-definition television.

FIG. 3C depicts the synthetic scene of FIG. 3B, but the RGB color modelof the right-half has been modified; the three-channel image has beenconverted to a single-channel image. To calculate intensity Y of asingle-channel grayscale color model from a three-channel RGB colormodel, BT.601 provides the following formula: Y=0.299R+0.587G+0.114B.Here, weights of 29.9%, 58.7%, and 11.4% have been applied to theR-channel, G-channel, and B-channel. Application of the BT.601 formulato colors of the runway border 202, location highlighter 204, and sky206 of FIG. 3B results with a single intensity for the following colors:black (0), magenta (105), and sky blue (103). In the grayscale colormodel with a 0-255 channel range, an intensity of 0 is black and anintensity of 255 is white. That is, black indicates 0% intensity, andwhite indicates 100% intensity; falling between black and white areshades of gray; as embodied herein, black and white may be considered ashades of gray. Accordingly, application of the BT.601 formula resultswith a single intensity for the following colors (or percent shades ofgray): black (0%), magenta (41%), and sky blue (40%). As recognized inFIG. 2C, the shades of gray of location highlighter 208 (41%) and sky210 (40%) appear with nearly identical. When projected onto a HUDcombiner unit, location highlighter 208 and sky 210 could be lightedwith approximately the same intensity of HUD monochrome color; andrunway border 202 will not be lighted because black is indicative of HUDcombiner transparency.

FIG. 3D depicts the synthetic scene of FIG. 3B, but the RGB color modelof the right-half has been modified; the three-channel image has beenconverted to a single-channel image. To calculate intensity Y of asingle-channel grayscale color model from a three-channel RGB colormodel, BT.709 provides the following formula: Y=0.2125R+0.7154G+0.0721B.Here, weights of 21.25%, 71.54%, and 7.21% have been applied to theR-channel, G-channel, and B-channel. Application of the BT.709 formulato colors of the runway border 202, location highlighter 204, and sky206 of FIG. 3B results with a single intensity for the following colors:black (0), magenta (73), and sky blue (112). That is, application of theBT.709 formula results with a single intensity for the following shadesof gray: black (0%), magenta (28%), and sky blue (44%). As recognized inFIG. 3D, the shades of gray of location highlighter 212 and sky 214 arereadily apparent with the sky 214 appearing darker that locationhighlighter 212. When projected onto a HUD combiner unit, sky 214 couldbe more lighted than location highlighter 212, and runway border 202could be transparent.

FIG. 3E depicts the synthetic scene of FIG. 3B, but the RGB color modelof the right-half has been modified; the three-channel image has beenconverted to a single-channel image. To calculate intensity Y of ared-only single-channel color model from a three-channel RGB colormodel, only the primary color red has been extracted; in other words,full weight has been provide to red as indicated in the followingformula: Y=1.00R+0.00G+0.00B. Application of this formula to colors ofthe runway border 202, location highlighter 204, and sky 206 of FIG. 2Bresults with a single intensity for the following colors: black (0),magenta (255), and sky blue (0). That is, application of the formularesults with a single intensity for the following shades of gray: black(0%), magenta (100%), and sky blue (0%). Because 0% intensity indicatesblack and 100% intensity indicates white, the white of locationhighlighter 216, and the black of sky 218 and runway 202 of FIG. 3E areeasily recognized. When projected onto a HUD combiner unit, locationhighlighter 212 could be fully lighted, and sky 214 and runway border202 could be transparent.

FIG. 3F depicts the synthetic scene of FIG. 3B, but the RGB color modelof the right-half has been modified; the three-channel image has beenconverted to a single-channel image. To calculate intensity Y of agreen-only single-channel color model from a three-channel RGB colormodel, only the primary color green has been extracted; in other words,full weight has been provided to green as indicated in the followingformula: Y=0.00R+1.00G+0.00B. Application of this formula to colors ofthe runway border 202, location highlighter 204, and sky 206 of FIG. 3Bresults with a single intensity for the following colors: black (0),magenta (0), and sky blue (136). That is, application of the formularesults with a single intensity for the following shades of gray: black(0%), magenta (0%), and sky blue (53%). Because 0% intensity indicatesblack, the black of location highlighter 220 and runway 202, and theapproximate medium shade of gray of sky 222 are readily apparent. Whenprojected onto a HUD combiner unit, location highlighter 220 and runwayborder 202 could be transparent, and sky 222 could be partially lighted(53% lighted).

FIG. 3G depicts the synthetic scene of FIG. 3B, but the RGB color modelof the right-half has been modified; the three-channel image has beenconverted to a single-channel image. To calculate intensity Y of ablue-only single-channel color model from a three-channel RGB colormodel, only the primary color blue has been extracted; in other words,full weight has been provided to blue as indicated in the followingformula: Y=0.00R+0.00G+1.00B. Application of this formula to colors ofthe runway border 202, location highlighter 204, and sky 206 of FIG. 3Bresults with a single intensity for the following colors: black (0),magenta (255), and sky blue (204). That is, application of the formularesults with a single intensity for the following shades of gray: black(0%), magenta (100%), and sky blue (80%). Because 0% intensity indicatesblack, 100% indicates white, and 80% intensity indicates a lighter ofgray, the white of the location highlighter 216, the white of locationhighlighter 224, the black of runway 202, and the lighter shade of grayof sky 226 and of FIG. 3E are easily recognized. When projected onto aHUD combiner unit, location highlighter 212 could be fully lighted, sky214 could be partially lighted (80%), and runway border 202 could betransparent.

In the preceding examples of FIGS. 3B through 3G, inclusive, asingle-channel color model has been derived by weighting each channel ofthe multi-channel color model to arrive at a weighted sum intensity ofthe single-channel. Through comparison, a red-only color model of FIG.3E could produce a favorable result in some circumstances. Thethree-channel color of sky blue (0, 136, 204) of sky 206 has produced asingle-channel color of black (0) of sky 218 after full weight has beingapplied to red. The resultant 0% intensity for the depiction of the skyon a HUD correlates to a favorable, fully transparent image whichresults with no image being projected onto the combiner unit which mayobscure the pilot's vision of the sky in the scene outside of aircraft.Also, a side-by-side comparison of the terrain in FIG. 3E may indicate amore favorable and consistent deception of mountainous terrain with aconversion to a red-only color model. Moreover, a side-by-sidecomparison of the mountainous terrain in FIG. 3G indicates that ablue-only color model may produce the least favorable depiction of bothsky 226 and mountainous terrain.

Although a single-channel color model may provide favorable results insome circumstances, it may not provide such favorable results in others.For example, a green-only color model could produce a more favorableimage of lower-lying terrain. A side-by-side comparison of thelower-lying terrain 228 and terrain 230 in FIG. 3F indicates that thesynthetic scene converted from the three-channel RGB color model to agreen-only color model could produce a more favorable depiction of thelower-lying terrain than that of FIG. 3E. Moreover, a side-by-sidecomparison of the lower-lying terrain in FIG. 2G indicates that ablue-only color model may produce the least favorable depiction.

Although conversion to a single-channel color model may not produce themost favorable results in all circumstances, chroma keying could beemployed to address specific conditions. That is, a chroma key could beemployed conditionally. An example of such a condition is with thedepiction of the sky. If the sky is represented by the color of sky bluein the generation of the SVS synthetic scene, then a sky blue chroma keycould be assigned to the multi-channel pixel intensity corresponding tothe color of sky blue. If the sky blue chroma key is matched with thepixel intensity, then the pixel intensity could be modified so that adesired single-channel pixel intensity corresponding to sky blue wouldresult after the application of a conversion formula. Because knowledgeof a conversion formula is necessary to achieve the desiredsingle-channel pixel intensity after conversion, the selection of achroma key may be dependent upon a conversion formula.

Here, sky blue pixel intensity (0, 136, 204) may be modified to a skyblue chroma key (0, 0, 0). Then, upon conversion to a single-channelcolor model using a conversion formula, the desired 0% intensityrepresented by the color of black (0) may result. If the color of skyblue were assigned to depict the sky, then various shade(s) of bluecould be used during the creation of the synthetic scene for depictingwater such as lakes, rivers, reservoirs, etc. . . . so that a sky bluechroma key would not affect various shades.

Another example of a condition which could employ a chroma key is withthe depiction of a runway and runway markings. A resultant 0% intensityfor the depiction of a runway and markings on a HUD correlates to afavorable, fully transparent image which results with no image beingprojected onto the combiner unit which may obscure the pilot's vision ofthe runway in the scene outside of the aircraft. In other words, thepilot will have a view of the runway unobstructed by a synthetic image.

If specific colors of an RGB color model have been assigned to depict arunway and runway markings in the generation of the SVS synthetic scene,these colors could be represented in a gray scale with a range betweenand inclusive of white (255, 255, 255) and black (0, 0, 0), where pixelintensity in each channel of a multi-channel color model may equal eachother. For example, runway 202 in the drawings of FIG. 3 could employ awhite pixel intensity (255, 255, 255) for runway markings, one shade ofgray for runway edges (100, 100, 100), and a second shade of gray forthe runway center (50, 50, 50). Here, any runway multi-channel pixelintensity in which the pixel intensity for each channel equals eachother (x, x, x) may be modified to a runway chroma key (0, 0, 0). Thatis, a chroma key may be assigned to the specific multi-channel pixelintensity values where the pixel intensity value of each channel equalsthe other. Then, upon conversion to a single-channel color model using aconversion formula, the desired 0% intensity represented by the color ofblack (0) may result for the runway and runway markings.

Another example of which a condition which could employ a chroma key iswith the depiction of terrain. If specific colors of an RGB color modelhave been assigned to depict specific elevation ranges in the generationof the SVS synthetic scene, then a specifically-weighted chroma keycould be assigned to the pixel intensity of each elevation range toachieve an optimal depiction of terrain; if a specifically-weightedchroma key matches one of the specific RGB pixel intensities, then thepixel intensity could be modified so that a desired single-channel pixelintensity corresponding to the specific color would result after theapplication of a conversion formula.

In another condition, a chroma key could be based on geographic locationwhere ranges of terrain elevations may be considered in a same categoryif data representative of aircraft location is provided to an IGprocessor. For example, terrain elevations in the plains area of theUnited States between the Appalachian Mountains and Rocky Mountains maybe generally categorized as falling within a range of relatively lowelevations. If this range is represented by a shade(s) of green in thegeneration of the SVS synthetic scene, then a weighted chroma keyfavoring green predominately and red to a lesser extent could beassigned to each multi-channel pixel intensity corresponding to ashade(s) of green. If a weighted chroma key is matched with the pixelintensity, then the pixel intensity could be modified so that a desiredsingle-channel pixel intensity corresponding to the shade of green wouldresult after the application of a conversion formula.

Likewise, terrain elevations in the Rocky Mountains may be generallycategorized as falling within a range of relatively high elevations. Ifthis range is represented by a shade(s) of brown in the generation ofthe SVS synthetic scene, then a weighted chroma key favoring redpredominately and green to a lesser extent could be assigned to eachmulti-channel pixel intensity corresponding to a shade(s) of brown. If aweighted chroma key is matched with the pixel intensity, then the pixelintensity could be modified so that a desired single-channel pixelintensity corresponding to the shade of brown would result after theapplication of a conversion formula.

FIG. 4 depicts a flowchart 300 of an example of a method for generatingHUD image data from synthetic image data. The flowchart begins withmodule 302 with the receiving of multi-channel pixel intensity data byan IG processor 130. As embodied herein, multi-channel pixel intensitydata (or color intensity data) could be provide by an SVS 110. In oneembodiment, a multi-channel pixel intensity data may be representativeof a three-dimensional lighted solid image. In another embodiment, themulti-channel pixel intensity data set could include data representativeof at least one location highlighter, shading effect, and/or texturingeffect, so that the synthetic image may include at least one of these.As embodied herein, the receiving of data by an IG processor 130 or theproviding of data to an IG processor may include a step in which the IGprocessor performs a retrieval operation of such data.

In an additional embodiment, the multi-channel pixel intensity datacould be modified by one or more chroma keys where each chroma key couldbe assigned to a specific multi-channel pixel intensity value including,but not limited to, a value associated with the color of a sky color,the gray colors of a runway and runway markings, or the color ofterrain. In another embodiment, an IG processor 130 could also receivedata representative of aircraft position, and each chroma key could havea specific multi-channel pixel intensity value assigned to it.

The flowchart continues with module 304 with the generating ofsingle-channel pixel intensity data as a function of the multi-channelpixel image data set and channel weighting. A multi-channel pixelintensity data set may be converted to a single-channel data set using aweighted conversion formula programmed for use by IG processor 130. Asembodied herein, a weight conversion formula could include, but is notlimited to, a published formula and/or a formula derived to extract onecolor channel from a multi-color channel color model. As a result of aconversion, a lighted solid terrain image comprised of a plurality ofintensities of a single color may be generated.

The flowchart continues to module 306 with the providing of asingle-channel intensity data set to a HUD system for display on a HUDcombiner unit of an image data set by an IG processor 130. Asingle-channel intensity data set could represent a lighted solid imageof terrain that is depicted in one color, where changes in terrainelevation or terrain contours or location highlighters may be presentedwith different color intensities of the same color. As embodied herein,such location highlighters and/or color intensity data may beconfigurable by a manufacturer or end-user and may include, but are notlimited to, data relating to shading effects and texturing effects.Then, the flowchart proceeds to the end.

It should be noted that the method steps described above may be embodiedin computer-readable media as computer instruction code. It shall beappreciated to those skilled in the art that not all method stepsdescribed must be performed, nor must they be performed in the orderstated.

As used herein, the term “embodiment” means an embodiment that serves toillustrate by way of example but not limitation.

It will be appreciated to those skilled in the art that the precedingexamples and embodiments are exemplary and not limiting to the scope ofthe present invention. It is intended that all permutations,enhancements, equivalents, and improvements thereto that are apparent tothose skilled in the art upon a reading of the specification and a studyof the drawings are included within the true spirit and scope of thepresent invention. It is therefore intended that the following appendedclaims include all such modifications, permutations and equivalents asfall within the true spirit and scope of the present invention.

1. A system for generating head-up display (“HUD”) image data fromsynthetic image data, such system comprising: a source of amulti-channel pixel intensity data set comprised of synthetic image datarepresentative of a three-dimensional, multi-color perspective of asynthetic terrain image, where the synthetic terrain image is beingpresented on a head-down display (“HDD”) unit; an image generatingprocessor configured to receive a multi-channel pixel intensity data setcomprised of the synthetic image data, generate a single-channel pixelintensity data set as a function of at least the multi-channel pixelintensity data set and channel weighting, where the single-channel pixelintensity data set is representative of a non-wireframe, single colorperspective of the synthetic image data, where the perspective has thevisual appearance of a three-dimensional, lighted solid terrain imageformed by varying the brightness of the single color, such that  changesin terrain elevation are indicated by varied brightnesses of the singlecolor, whereby  darker and lighter areas of the three-dimensional,lighted solid terrain image comprised of the varied brightnessescorrelate to greater and lesser transparencies of a head-up displayunit, respectively, and provide the single-channel pixel intensity dataset to a HUD system; and the HUD system configured to receive thesingle-channel pixel intensity data set, and display the perspective ofthe synthetic image data represented in the single-channel pixelintensity data set on a HUD combiner unit of the HUD system.
 2. Thesystem of claim 1, wherein the multi-channel pixel intensity data setincludes data representative of at least one location highlighter,shading effect, texturing effect, or a combination thereof, whereby thesynthetic image includes at least one of these.
 3. The system of claim1, wherein the processor is incorporated into an existing avionicssystem.
 4. The system of claim 3, wherein the existing avionics systemincludes a synthetic vision system or the HUD system.
 5. The system ofclaim 1, wherein the image generating processor is further configured tomodify the multi-channel pixel intensity data set, where themulti-channel pixel intensity data set is modified through the use of atleast one chroma key.
 6. The system of claim 5, wherein each chroma keyis assigned to a specific multi-channel pixel intensity value.
 7. Thesystem of claim 1, further comprising: a navigation system for providingdata representative of aircraft position, and the image generatingprocessor is further configured to receive the data representative ofaircraft position, and modify the multi-channel pixel intensity dataset, where the multi-channel pixel intensity data set is modifiedthrough the use of at least one chroma key corresponding to aircraftposition.
 8. The system of claim 7, wherein each chroma key is assignedto a multi-channel pixel intensity value.
 9. A module for generatinghead-up display (“HUD”) image data from synthetic image data, suchmodule comprising: an input communications interface to facilitate thereceiving of data by an image generating processor; the image generatingprocessor configured to receive a multi-channel pixel intensity data setcomprised of synthetic image data representative of a three-dimensional,multi-color perspective of a synthetic terrain image, where thesynthetic terrain image is being presented on a head-down display(“HDD”) unit, generate a single-channel pixel intensity data set as afunction of at least the multi-channel pixel intensity data set andchannel weighting, where the single-channel pixel intensity data set isrepresentative of a non-wireframe, single color perspective of thesynthetic image data, where the perspective has the visual appearance ofa three-dimensional, lighted solid terrain image formed by varying thebrightness of the single color, such that changes in terrain elevationare indicated by varied brightnesses of the single color, whereby darker and lighter areas of the three-dimensional, lighted solidterrain image comprised of the varied brightnesses correlate to greaterand lesser transparencies of a head-up display unit, respectively, andprovide the single-channel pixel intensity data set to a HUD system; andan output communications interface to facilitate the single-channelpixel intensity data set to the HUD system, whereby the perspective ofthe synthetic image data represented in the single-channel pixelintensity data set will be displayed on a HUD combiner unit of the HUDsystem.
 10. The module of claim 9, wherein the multi-channel pixelintensity data set includes data representative of at least one locationhighlighter, shading effect, texturing effect, or a combination thereof,whereby the synthetic image includes at least one of these.
 11. Themodule of claim 9, wherein the multi-channel pixel intensity data setcorresponds to the RGB color model.
 12. The module of claim 9, whereinthe module is incorporated into an existing avionics system.
 13. Themodule of claim 12, wherein the existing avionics system includes asynthetic vision system or the HUD system.
 14. The module of claim 9,wherein the image generating processor is further configured to modifythe multi-channel pixel intensity data set, where the multi-channelpixel intensity data set is modified through the use of at least onechroma key.
 15. The module of claim 14, wherein each chroma key isassigned to a specific multi-channel pixel intensity value.
 16. Themodule of claim 9, wherein the image generating processor is furtherconfigured to receive the data representative of aircraft position, andmodify the multi-channel pixel intensity data set, where themulti-channel pixel intensity data set is modified through the use of atleast one chroma key corresponding to aircraft position.
 17. The moduleof claim 16, wherein each chroma key is assigned to a multi-channelpixel intensity value.
 18. A method for generating head-up display(“HUD”) image data from synthetic image data, such method comprising:receiving a multi-channel pixel intensity data set comprised ofsynthetic image data representative of a three-dimensional, multi-colorperspective of a synthetic terrain image, where the synthetic terrainimage is being presented on a head-down display (“HDD”) unit; generatinga single-channel pixel intensity data set as a function of at least themulti-channel pixel intensity data set and channel weighting, where thesingle-channel pixel intensity data set is representative of anon-wireframe, single color perspective of the synthetic image data,where the perspective has the visual appearance of a three-dimensional,lighted solid terrain image formed by varying the brightness of thesingle color, such that changes in terrain elevation are indicated byvaried brightnesses of the single color, whereby  darker and lighterareas of the three-dimensional, lighted solid terrain image comprised ofthe varied brightnesses correlate to greater and lesser transparenciesof a head-up display unit, respectively; and providing thesingle-channel pixel intensity data set to a HUD system, whereby theperspective of the synthetic image data represented in thesingle-channel pixel intensity data set will be displayed on a HUDcombiner unit of the HUD system.
 19. The method of claim 18, wherein themulti-channel pixel intensity data set includes data representative ofat least one location highlighter, shading effect, texturing effect, ora combination thereof, whereby the synthetic image includes at least oneof these.
 20. The method of claim 18, further comprising: modifying ofthe multi-channel pixel intensity data set, where the multi-channelpixel intensity data set is modified through the use of at least onechroma key.
 21. The method of claim 20, wherein each chroma key isassigned to a specific multi-channel pixel intensity value.
 22. Themethod of claim 18, further comprising: receiving data representative ofaircraft position, and modifying the multi-channel pixel intensity dataset, where the multi-channel pixel intensity data set is modifiedthrough the use of at least one chroma key corresponding to aircraftposition.
 23. The method of claim 22, wherein each chroma key isassigned to a multi-channel pixel intensity value.